Container sterilizing



July 20 1926. 1,593,121

C. E. GRAY CONTAINER STERILIZING Filed July 29. 1922v 3 M Marianna Patented July 20, 1926.

CHESTER GRAY; or oAKrJAun, cararonnra.

CONTAINER STERILIZING.

Application filed July 29, 1922. Serial No. 578,361.

This invention relates to the sterilization of containers by means of steam and has for its object the provision of a system for eii'ectively sterilizing such containers as milk cans in a minimum of time and'in an economical manner. A further object of the invention is the provision of a system of appliances for conveniently carryingout the process. V f

Up to the.present'timef'tlrere ave been two general methods of treating containers, one of which is effective but'cumbersome, and the other of which is simple but not sufiiciently effective to satisfy the more 8X- acting modern conditions. In the first of these systems the containers are subjected to steam at high temperature in a closed chamber. If the containers are subjected to this treatment for a sufficient time, the containers will be found absolutely sterile, but it is not possible'to handle such objects as milk cans through such a system in an economical way and it has therefore been the universal custom to treat milk cans, etc, by the second method, that is, by injecting into the open can a jet of boiler steam which reaches the container walls at atmospheric pressure and never over 212 F.

Bacterial tests of cans treated in this manner show a surprisingly large number of uninjuredorganisms and tests to determine the reason for this have so far failed to give a clear and logical explanation. The metal walls of the vessel treated by saturated steam do not become more thanmoderately heated by the treatment and it is'noted'that a cloud of water vapor rushes from the mouth ofthe receptacle when so treated, even in states where low humidities a1 prevalent. p EXPGIlHlQllt has also shown that con tinned heating of the vessel by dry air at a high temperature, say 300 F., for a number of hours does not completely sterilize the container, but it has been found by the use of the apparatus illustrated in the pres ent application, that, if the pressure of the steam is lowered to a small figure, say 10 pounds gage pressure, and this steam is superheated-to approximately the temperature at boiler pressure, say 300 F., and this low pressure superheated steam is injected into a can or similar container, the temperature of the can itself rises almost to the temperature of the low pressure steam and that little or no condensed steam can be seen issuing from the mouth of the inverted vessel. I

It would thus seem that a very much greater percentage of the heat units of the steam are delivered to the walls of the container when using superheated steam than when using saturated steam. When the con tainers are treated with low pressure superheated steanutollowedby a blast of air, the containers areFtoundi to'be absolutely dry and as sterile asiftreated by the first method, i. e., sterilized in a closed chamber at high pressure and temperature.

A convenient system= of apparatus for carrying out the process of sterilizing and drying containers is shown in the drawings, in which,-

Figure 1 is a somewhat diagrammatic view of the apparatus.

Fig. 2 is an elevation of a modified form of the interchange piping.

Fig. 3 is a diagrammatic view showin the cans in the process of sterilizing and drying.

The boiler diagrammatically represented by the rectangle 11 delivers steam to pipe 12 at boiler pressure and temperature, pipe 12 discharging into a standard steam separator 14 having the usual gage glass 15 and discharging through a manually operated gate valve 16 to a steam trap 17 also of well known and standard type. Pipe 20 leads the steam from the separator to a pressure regulator 21 supplied with a recorder 22 in order that the pressure of the steam in the pipe 23 maybe kept at the desired figure CLO-pounds gage pressure having been found inpractic'e to give efiicient sterilization.

The pipe 'ds direct to the jets 25 p 'jssing' througl "an interchange pipe 28 having end caps29 and 30 and for ease of installation and repair may be provided with a plurality of Ts 82 and 33 the former communicating through pipes 35, 36 and 37 with the steam trap 17. The T33 communicates with the pipe 40 leading from the boiler pipe 12 and carrying a recording gage 41 similar to the gage 22.

In the modified form shown in Figure 2 the end caps 30 are replaced by caps 30 so as to permit the use or a plurality of low pressure steam conveying pipes numbered 23 and being similar in general with the single pipe 23, each of the four pipes 23 leading to respective nozzles 25. The interchange pipe 28" and the T 32' will of course be of larger size than the corresponding elements in Figure 1 but the operation is exact.- ly similar in the two systems the advan tage of the modified form being quicker handling of the containers due to the use of a plurality of steam nozzles.

Figure 3 shows very diagrammaticallythe method of handling the cans. The can tainers, such for example as the metallic cans 43 and 44, are advanced preferably step by step. ina conveyor of any. desiredgtype. (not shown) dwelling at one step over a steam jet 25 and dwelling ,at the next step of the conveyor, over an air nozzle 45 injecting air which may oi'unay: not beheated and which maybe dehydrated if so desired The function of this air is to remove the steampresent in the container and which might condense thereinif the can were a l lowed to cool'bef-ore removalof the steam, It is my belief that the great superiority of this system, over that ofsystems using saturated steam is due tothe fact that in the older systems an appreciable amount of steam escapes from the. Container as-vapor, whereas the low pressure, superheated steam ives up a very large proportion of its super; heat to the wall ,ofthe container, heatingthe latter to a point above 212913., thus prevent,- ing-condensati-on of the steam to more than the slight amount necessary for most efli: cient sterilization. It isbclieved thatin using the high pressure saturated steam the steam expands so rapidly andv lowers .itstemperature so, quickly that, the walls of the container are not permittedto absorb heat sufficient toheat such walls to eventhetem; perature of boiling water. Cans treated with saturatedsteam;do,v of course, gethot, but; the temperature reached by the con; tainers. is only about 120 c0150? F., area general rule, and in 110. Case reaches. atem; perature overt 212v F., as contemplated by the present invention.

As has hereinhcforeibeen stated it seems thata lar 'er quantity of heat units is trans,- ferred to t 1e walls ofthe container YVhQIIll$7 ing superheated steam than when using saturated, steam and in view-of thefact that in actual practice it has been found that the containers are cleansed, as well as ster ilized, after. having been treated accordingto the present process, it is also my belief that the application of this increased; number of hcatunits is such as to raise the temperature ofthe container walls to a degree capable of liquefying fatty matter that is ordinarilyfound; upon the walls of containers treated with saturated steam. Where satr urated steam has been used for sterilizing aillQrs'g llie Said co tai ers rrs at 1 l in; containerwhile sald. Crammer; isstill' hotK 3. Theart or st izin'g, containers wvhjich sea st n iseli s n e'r' a' f 111 s a a was ia i l sli i e than atmospheric fissure and at. a t'emg 8s: Qata a urated.

mes e r n a ginltei mitteiltlyjmov -i first. past. a jet fi x i p il fi 1 a rto, drlve sa Y I F saidcontainer; 5. Thelarto terilijn' andfdryingeon tainers which consists in 'inteifmitt'ently moving a series, of w past a J's- 11w so 8 P; as an' an enipast- Jet; ta rfto I r senses r l se -ce tain r. 6. artoff, liz ing; and dryingcon; ai ersavh clr do .rlst-" ii r' lis a s egsuper h a dT' te t an i jta i i t' u h a rate qf flow; as toij'he' the containers to a temperaturegof atllea'st 'ilmf EQ l l 7 sterilizing containers which on sts n; e ea g; the moi u fr m steam' at boiler pressure"and"temperature; reducing-,- the pressure oi said stead; re at ng said r duced hre u e ts m t p: p im e y its ii s-iaal mperatma idjin d sch r ng Se" {ml sat l t Pressu s m int ra aste? aa tr s li i .-v T e a t Qt aeaa aanei s whi nsis s n ch at -gins;-sape hea edi q sure; a sa d: et taine a eam h 

